Rest Assured: The Brain Practices the Day's Lessons as We Sleep

Are you sleeping well these days? You know, it's still amazing to me that experts haven't reached a consensus on what the exact purpose of sleep is.

One possibility is that it helps us build memory and problem solve.

In 1994 neuroscientists at the University of Arizona recorded the brain activity of rats as they navigated mazes and noted that specific brain cells (called "place cells") fired at specific spots along the route.

Then as the rats slumbered that night, scientists found the same cells firing, in the same order. The rat's brains were practicing running through the maze as they slept!

Researchers believe that the brain reactivates patterns of neural connections it made during the day—thus strengthening long-term memory during the night.

A 2005 fMRI study of pianists learning a complicated score found that they engaged different brain areas for the task, and that they performed better, only after snoozing.

During sleep, memory was specifically strengthened in the optimal brain areas for that task—those known to control hand movements. And these were different from the areas activated during the initial learning of the sequence.

Read about these and other sleep studies in the August/September issue of Scientific American MIND. Then, sleep on it.

保證睡眠：當我們睡覺的時候，大腦仍然在處理我們白天所學的知識。

你這幾天睡得還好嗎？你可能知道，專家們目前對睡眠的確切目的還不能達成一致意見，對這一點我仍然感到奇怪。

 其中一種可能性就是睡眠幫助我們強化記憶和解決問題。

在1994年亞利桑那大學的神經科學家們做了個實驗，他們紀錄了老鼠闖迷宮時的腦活動。科學家們發現老鼠的一些特定腦細胞（叫做“位置細胞”）在老鼠處于迷宮途中的特定地點時表現活躍。

當晚這些老鼠睡覺的時候，科學家們發現這些相同的腦細胞表現出相同程度的活躍。老鼠的大腦在它們睡覺的時候還在鍛煉闖迷宮呢！

研究人員認為大腦把白天形成的神經聯系重新激活——也就是說在晚上長期記憶得到了加強。

研究人員在2005年對學習一篇復雜樂譜的鋼琴家們進行了功能性核磁共振成像（Functional Magetic Resonance Imaging, fMRI）研究，結果表明，不同大腦區域參與到樂譜學習之中；研究同時發現只有在鋼琴家們得到睡眠之后他們才演奏得更好。

 在睡眠的時候，記憶特別在負責記憶任務的最佳大腦區域得到加強---那些控制手活動的區域。這些區域不同于剛開始學習序列時候那些被激活的區域。

《科學美國人》的8-9月“心理”欄目有更多關于睡眠的研究，你可以進一步閱讀了解。讀完之后，睡個好覺吧！

Vocabulary:
Consensus: 一致
Neuroscientist: 神經科學家
Navigate: 航行；領航
Maze: 迷宮
Fire: 興奮
Slumber:  睡眠
Score: 樂譜
Snooze: 小睡；打盹兒
Sequence: 序列